Use parameter packs instead of macro sequence generators where possible
Started extending tagged_ptr_union to hold more than 2 pointers

Removed pcomn::bor, band, bxor, bnot - there are std counterpart now (bit_or, etc.)

Simplified ct_lnzbpos, ct_log2floor, ct_log2floor, implemented 64-bit versions

ct_min<>, ct_max<> accept arbitrary number of arguments now
Generalize tagged_ptr_union to number of types greater than 2

Implemented count_types_if trait